Startup circuit for bandgap voltage reference generators

a voltage reference and start-up circuit technology, applied in the direction of electrical variable regulation, process and machine control, instruments, etc., can solve problems such as voltage monitoring

Active Publication Date: 2011-01-13
DIALOG SEMICONDUCTOR GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0021]In accordance with the objects of this invention a startup circuit of bandgap voltage reference generator circuits monitoring a current flow in the bandgap voltage reference generator circuit has been disclosed. The startup circuit invented comprises, firstly, a first circuit branch, comprising a first transistor and a first diode, which has been replicated from a branch of the bandgap voltage reference generator circuit, wherein the current through said branch of the bandgap voltage reference generator circuit is mirrored to said first branch, and wherein said first branch is connected between Vdd voltage and ground, a current detection unit having inputs and an output, wherein a first input is a current through said first diode, a second input is

Problems solved by technology

The disadvantage of monitoring a voltage is that the voltage monitoring is performed by a voltage comparator, which requires a specific voltage for its operation and a reference voltage.
It is a challenge for the designers of startup circuits for bandgap voltage reference generators to design a circuit wherein the startup condition is process independent because a threshold voltage of NMOS or PMOS devices is used as reference and wherein no reference voltage is required for the startup.

Method used

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  • Startup circuit for bandgap voltage reference generators
  • Startup circuit for bandgap voltage reference generators
  • Startup circuit for bandgap voltage reference generators

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Embodiment Construction

[0027]Circuits and methods for a startup bandgap voltage reference generator are disclosed. Instead of monitoring a voltage as usually performed in prior art, the startup circuit of the present invention monitors a current flow in the bandgap voltage reference generator circuit. The startup circuit operates using supply voltages in the order of about a threshold voltage of a PMOS or NMOS device and is therefore appropriate for low voltage applications.

[0028]In addition the need for a voltage reference is removed. The advantage of this is that the startup condition is semiconductor process independent because in prior art often the threshold voltage of MOS devices is used as reference voltage.

[0029]FIG. 1 illustrates a principal schematic of a current-mode bandgap voltage reference generator driven by startup circuit of the present invention. The circuit of FIG. 1 has two parts, a startup circuit 1 invented and a current-mode bandgap voltage reference generator 2. It should be noted ...

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Abstract

Systems and methods to achieve a startup circuit of bandgap voltage reference generator circuits monitoring a current flow in the bandgap voltage reference generator circuit have been achieved. The startup circuit can operate at supply voltages of about one threshold voltage and is therefore appropriate for low voltage applications. The monitoring of a current through an electrical component inside the bandgap voltage reference generator circuit by replication the component branch in a scaled version saves power and does not disturb the normal operation of the current-mode bandgap voltage reference generator. The startup circuit invented can be applied for current-mode bandgap voltage reference generator circuits as well as for voltage-mode bandgap voltage reference generator circuits.

Description

BACKGROUND OF THE INVENTION[0001](1) Field of the Invention[0002]This invention relates generally to bandgap voltage reference generators and relates more specifically to a startup circuits for bandgap voltage reference generators.[0003](2) Description of the Prior Art[0004]Typical bandgap voltage reference generator circuits are self-biased and have two stable bias-points, a desired operational bias point for which the circuit has been designed for and an undesired bias-point where the bandgap output voltage reference remains at 0 V. A dedicated startup circuit is required to ensure that the bandgap voltage reference generator is brought to an operating range where it can obtain the desired bias-point.[0005]Current practice is to monitor a voltage inside the bandgap voltage reference generator and to initiate a current flow into the bandgap reference voltage generator circuit as long as the voltage monitored does not have the operation condition required. The disadvantage of monito...

Claims

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Application Information

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IPC IPC(8): G05F3/16
CPCG05F3/30
InventorSTELLBERGER, ACHIMSCHWIDERSKI, FRANK
OwnerDIALOG SEMICONDUCTOR GMBH